Abstract:

Effects of exogenous salicylic acid (SA) on nitrate accumulation and light absorption and utilization of photosystem Ⅱ (PSⅡ) in the leaves of Chinese chive under high temperature stress were studied. The activity of nitrate reductase (NR) in nitrogenous metabolism was depressed under high temperature and the nitrate content was increased. The activity of NR was significantly increased and the nitrate content was decreased obviously by spraying exogenous SA than comparison. At the same time, the chlorophyll content, PSⅡ maximal photochemical (Fv/Fm), PSⅡ effective quantum yield [Y(Ⅱ)], photochemical quenching (qP), original quantum efficiencies (Q) and maximum electron transfer rate (ETRmax) significantly increased, but nonphotochemical quenching (NPQ) decreased obviously. Therefore, exogenous SA showed a positive role in reduction and assimilation of nitrate nitrogen, meanwhile it relieved the damage in the photosynthetic system under high temperature stress, improved the light use efficiency of the Chinese chive’s leave, in order to assure the process of nitrate assimilation smooth going.